Carvers Gap

That is the type of storm which can change up the entire NA wx pattern if it deepens an eastern trough. It has been there for several days, but that is a pretty big run for the NE.

Too warm on that run, but that is a FORMIDABLE solution on the 12z GFS around Feb 18th. That is likely a blizzard for portions of New England and inland mid-Atlantic. SLP rapidly deepens. If we can get that cold front to speed up, that is a big storm.....

The 12z EPS has a monster NAO which suppresses the storm track after Feb 24th. At minimum, the mountains should get hammered.

And if that get trapped under that block, it may well just not move.

That is pretty impressive, and this is how Atlantic blocking "could" help. The run to run departures right now are impressive to say the least. This is the 500 pattern from 12z. The NAO basically forces the PNA to pop by driving a piece of the TPV directly into the Lakes. That puts the boundary for winter storms over the TN and Ohio Valleys. Anyone remember what this looks like? Hint: don't look back too far. And yes, the sound is muted....!!!

The 12z GFS at 342 is a great illustration of one possibility of what happens just after the NAO tries to hook into the SER. Impressive stuff.

This is the run-to-run temperature change for the GFS...and this is just roughly 9 days out. To me, this implies very cold air is about to enter the pattern when models swing like this. That is about as wild as it gets from run-to-run.

Been a pretty consistent look during that time frame. A strong cold front driving this far south during February is likely going to get a reaction. Cosgrove has a great post today about all of that.

This is why we have to be careful to write-off winter - me included. If the 12z CMC is even remotely correct, the Euro MJO plots are in error. Now, I think it warms up right after this, and then gets cold again after that. It is that subsequent warm-up that modeling whiffed on. A detail like that will get washed out at range on an extended map. The 12z GFS has us in the 20s for the timeframe shown below. The CMC does have a cold bias, but it will often nail a cold shot at this range. It got the mid-January cold shot.

Actually, LR ext modeling has been exceptional this winter. 4-6 week modeling is going to miss at times. We still don't know yet if it has missed for the 14th to the 7th. Sure looks like it is set to miss for at least part of that time frame, and that happens in this hobby. What we do know is that it really doesn't get cold during phases 4-6 very often during winter, and we have just been reminded of that. Modeling has also been struggling mightily w/ the MJO. Here are this morning's updated extended plots. One is warm and one is cold. Now, those are derived from yesterday's runs. If the Euro is correct, winter is over. If the GMON is correct, winter is still breathing. Now, the GFS suite was really the first to see the trek into the warm phases. The Euro has tended to go COD this winter(over and over again), and has been in error each time. The CFS MJO from today looks decent...beware of solutions which go into the COD as that has been an error all winter. To me, this makes more sense. I am about 50/50 that winter is over with the exception of a well-placed, bowling ball. There are a wide range of MJO solutions right now, but they tend to lean towards either a fast trek through the cold phases or not at all. If forced to make a choice, what do I think? I tend to think cold is still on the table. Why? The -NAO. Modeling will be very, very slow to trend towards the consequences of that block at our latitude. As evidence, modeling was very late in recognizing the details of the mid Jan cold outbreak which was NAO driven if I remember correctly. I tend to think we see the NAO try to hook into the SER, and that is what is driving modeling nuts! It is what is after that which I am interested in. After that, could be a very significant cold shot. This is almost exactly a repeat of the pattern in January - even the comments in our forum are nearly identical to that lead-up. When/if the NAO matures, it could well send the mother load, and modeling will be late in seeing that. So, it is very wise to temper expectations, but I would hesitate in completely throwing out winter completely. Winter may well be over, but a late Feb/early March NAO is formidable(and VERY difficult to predict) and I highly doubt that is worked out yet. This is probably, as Holston points out, a situation where delayed is more likely than denied. I think the map below is a strong possibility. Crap Pacific, but the Atlantic tries to works some magic just after the NAO hooks into the SER. Beware of the big red ball over Davis Straits.............if real, it is going to have a say. And a very decent look on the 12z GFS mid-month to boot.

I should add the NAO will likely drive the pattern for the 2-3 weeks beginning around Feb 14...complete with hooking into the SER for a short time after the 20th. But right before the NAO exits is when I expect it to be the most cold. That is prob late Feb or early March. Be thankful for the NAO, if it wasn’t there....it would be 70+ each day. The biggest issue is that our source regions are very warm thanks to the MJO driven sauna. Remember that modeling erroneously had the cold continuing through the warm phases. It is possibly making the same mistake now by perpetuating warmth during cold phases.

I had a longer post, but here is the bottom line. The pattern flip is still there. The cold to fill the eastern trough is largely absent on the GFS easily in the pattern change. This change is eerily similar to late December. 500 flipped but temps took some time to adjust downward. It wasn’t until mid Jan that the pattern matured. Also, modeling at the time completely missed that last cold shot embedded in the pattern, and then missed the warmup. I think that MJO makes a full transit for the colder phases of those plots. I doubt modeling has accounted for that yet. I do think a warmup is embedded now in that pattern change, and that reflects the confusion in modeling that we have seen for a few days. Once the MJO transits 8–1-2-3, winter is over for the valleys most likely. I think the West is in for a very cold end to their winter in late March as the SSW is set to clock them.

Again, something is probably in error...either the CPC MJO plots or recent trends in modeling. My money is on colder solutions. It could be we have a ridge rolling through the northern Plains w/ cold right behind it in the d10-15....can't tell at the moment.

Pretty miserable pattern - BN temps but not really cold enough for snow. That could change. I have been watching the trend since yesterday evening. The NAO is still there , but we are highly likely losing the Pacific. The only good thing(if you can call it that) is that the MJO and modeling don't jive. If global modeling is in error or the MJO is in error for CPC (one of them is wrong I think), then we are about to see some changes in modeling for the much warmer or the much colder - not a lot of space for a happy medium. The pattern is still going to change. That is not really the issue. The problem is that source regions are just hot garbage. And in February (especially late), source regions are important. As of now, I think our chances for more snow are dropping rapidly after the 25th. Prob going to have to score before then or hit a bowling ball late.

BN temps are still being shown, but source regions are too warm for anything other than a perfectly placed storm and cold rain.

Significant warming trend after the 20th which was not expected...is being shown since 0z last night. Could this be an error such as we saw in January? Maybe. The MJO is set to transit the cold phases and modeling may be well behind in terms of trends - I suspect this. That said(verbatim) what is being shown on modeling this afternoon is the last gasp of winter. Let's hope it is wrong.

12z GFS wasn't too shabby for E TN and NE TN. Good to see that storm still on modeling. There is a chance that could be a good storm for the southern half of the forum area. Blocking should be in full effect by that time.

It "appears" that modeling(reference CPC MJO) has settled on passing through the colder phases of the MJO 8-1-2-3. That should roughly coincides w/ Feb 14-March7. We will see if the MJO loops back into colder phases after that. My guess is that modeling is missing a pass through warmer phases after March 7th...but for now, LR ext modeling is fairly adamant of a 4-6 week cold shot. I tend to think 3 to be on the safe side.

It still looks like about 5 days out from the pattern flipping. Like early January, I think we will see some cool air masses roll through in waves, and then a colder air mass drop into the pattern around the 20th. The 6z GFS has the bigger storm back around that time as well. At 12 days out, I am not sweating the details. But on this run, we would have been sweating as the cold was a half day behind the storm. I do think between the 13th and 20th, we will see short warm-ups between cold shots. That is common for late winter and early spring, and I expect that to be a commonality throughout most of the timeframe from Jan13-March7. The cold (on the weeklies) lasts well into March. I don't know if I buy that, but we'll see. Nino springs can be quite cold IF Nino hangs on that long(which I doubt it does). If La Nina takes over quickly(which it will prob be in transition), May could be very hot. Nina summers lately have been wicked hot(say it like you are from Boston). I don't look forward to those - drought and heat. Hopefully, this Nina stays weak. If it does, next winter could be good. Regardless, I do expect extended summer to last well into early October. If it goes moderate strong to strong....gonna be throwing a heater. Yes, I am throwing some baseball themed references in there.

Possibly. I rule out very few things when it comes to weather. A cold pattern tends to squash severe season as Jax alluded to a few pages ago. A warm spring is what is exponentially dangerous. When this potentially cold pattern breaks, I think the warm that follows could be treacherous in that regard.

I think this is going to come in waves. Spring will fight back in between cold shots....but good looking pattern coming together. As long as we have the Pacific, I think we are good.

The 12z CMC is just ridiculously cold.

Ah, yeah. I don't even look at details at this range. I just want a storm to our southeast from this far out, and cold coming in. If we can get a storm on the front edge of that cold air mass, then someone in the forum area is likely in business.

That is a pretty brutal cold outbreak following that storm. So, seems to me that modeling is "trying" to form a from on a polar/arctic boundary. That makes sense. That doesn't guarantee a storm, but that is a plausible solution.

What went poof? Not following.